When healthy, intervertebral discs located between endplates of adjacent vertebrae stabilize the spine and distribute forces between the vertebrae and cushion vertebral bodies. However, the spinal discs may be displaced, damaged, or degraded due to trauma, disease or aging. A herniated or ruptured annulus fibrosis may result in nerve damage, pain, numbness, muscle weakness, and even paralysis. Furthermore, as a result of the normal aging processes, discs dehydrate and harden, thereby reducing the disc space height and producing instability of the spine and decreased mobility.
In many instances, one or more damaged structural body parts can be repaired or replaced with a prosthesis or implant. For example, typical surgical correction of a collapsed disc space includes a surgical removal of the damaged vertebra (in whole or in part) and/or the damaged disc (in whole or in part) followed by the insertion of an implant or prosthesis. In some cases, it is necessary to stabilize a weakened or damaged spinal region by reducing or inhibiting mobility in the area to avoid further progression of the damage and/or to reduce or alleviate pain caused by the damage or injury. In other cases, it is desirable to join together the damaged vertebrae and/or induce healing of the vertebrae. Accordingly, an implant or prosthesis may be configured to facilitate fusion between two adjacent vertebrae. The implant or prosthesis may be placed without attachment means or fastened in position between adjacent structural body parts (e.g., adjacent vertebral bodies).
Access to a damaged disc space may be accomplished from several approaches to the spine. One approach is to gain access to the anterior portion of the spine through a patient's abdomen. However, extensive vessel retraction is often required and many vertebral levels are not readily accessible from this approach. A posterior approach may also be utilized, but this typically requires that both sides of the disc space on either side of the spinal cord be surgically exposed. This may require a substantial incision or multiple access locations, as well as extensive retraction of the spinal cord.
To alleviate problems associated with both anterior and posterior approaches to the spine, a lateral approach to the disc space may be utilized. A lateral approach is a minimally-invasive surgical approach providing such benefits including minimal tissue damage and blood loss, smaller incisions and resulting scars, reduced post-operative discomfort, and reduced time needed for recovery. However, difficulties remain in placing prostheses of sufficient size to stabilize the spinal segment while also adhering to or otherwise allowing reduced incisions for surgical access to the tissue site. Moreover, the minimal size of the access can hamper accurate positioning of the prosthesis once inside the intervertebral space. Even further, due to variations in patient and/or intervertebral cavity sizes, it is often necessary to employ a range of differently-sized prosthesis that may need to be tried before selecting the best fit for a particular patient.
Accordingly, it is desirable to provide an implant that can be easily inserted in accordance with a specific pathway or approach, such as a lateral approach, and that further eases obtaining a desired prosthesis position and resulting spinal segment stabilization.